Lens surfacing machine



April 4, 1961 w. J. KENNEDY ETAL LENS SURFACING MACHINE Filed Aug. 24,1959 FIG.

4 Sheets-Sheet 1 INVENTORS WILLIAM J. KENNEDY AND BY STsNLEY F.HOSTETLER April 4, 1961 w, EN ED ETAL 2,977,724

LENS SURFACING MACHINE Filed Aug. 24, 1959 4 Sheets-Sheet 2 m" cu Q o EINVENTORS WILLIAM J. KENNEDY AND BY STANLEY F. HOSTETLER April 1961 w.J. KENNEDY ETAL 2,977,724

LENS SURFACING MACHINE Filed Aug. 24, 1959 4 SheetsSheet 3 ||o 67 29\IO? no I08 107 I09 1 Q II H5 128 II ||2 98 93 EL '97 95 |2| 9e 92 I20 98v 9 if 47 INVENTORS WILLIAM J. KENNEDY AND STANLEY E HOSTETLER April 4,1961 w. J. KENNEDY EI'AL 2,977,724

LENS SURFACING MACHINE Filed Aug. 24, 1959 4 Sheets-Sheet 4 LO Q I Q L rT L S2 & g u.

IN V EN TORS WILLIAM J. KENNEDY AND STANLEY F. HOSTETLER United StatesPatent "ice j 1 2,917,724 LENS SURFACING MACHINE William J. Kennedy,Geneva, and Stanley F. Hostetler,

Phelps, N.Y., assignors to Textron Inc., Providence. R.I., a corporationof Rhode Island Filed Aug. 24, 1959, Ser. No. 835,599 7 Claims. (Cl.51-124) The present invention relates to machines for surfacing lenses,"and more particularly to machines for lapping approximately spher'icalsurfaces on lenses.

In conventional lens lapping machines, a convex or a concave lap,depending upon whether the lens surface thatis to be lapped is concaveor convex, is engaged with the workpiece under pressure, and one or theother is rotated while a relative swinging movement is effected betweenthe two. In practically all lens surfacing machines that have been builtto date the oscillation is achieved by a crank or eccentric drive. Aneccentric or crank produces a simple harmonic motion. The velocitystarts at zero and builds up to a maximum when the crank has rotated 90,and then the velocity decreases to zero again through the other 90 ofrotation of the crank. With this type of drive there is a definite dwellat both ends of the stroke. When wear develops in such a machine thisdwell at the ends of the strokeis amplified. As a result zones orirregularities are produced on the lens surface.

. One object of the present invention is to provide a lens surfacingmachine in which the oscillatory motion is ef fected in such wise as-toreduce to a minimum the possibility of formation of zones orirregularities on the lens surface. To this end it is a further purposeof the invention to provide a lens surfacing machine in which thevelocity of the oscillatory motion is constant throughout the stroke ineither direction and the reversal at opposite ends of the stroke ispractically instantaneous.

Another object of the invention is to provide a machine of the characterdescribed in which the pressure between the lens and lap is alwaysapplied to the lens in a direction normal to the lap curvature.

Another object of the invention is to provide a machine of the characterdescribed in which the position of the Y 7 axis of oscillation and theextent of oscillation, as required by the particular lap in use, canvery readily be adjusted; Another object of the invention is to providea machine of the character described which will'be precise in operation,rigid in construction, and eificient in operation.

Other objects of the invention will be apparent hereinafter from thespecification and from the recital of the appended claims, particularlywhen read in conjunction with the accompanying drawings.

In the drawings: l Fig. 1 is a part side elevation, part verticalsectional view of a machine built according to one embodiment of thisinvention;

Fig. 2 is a plan view of this machine; Fig. 3 is a rear'elevation of themachine, part being broken away and shown in section; i

Fig. 4 is a front elevational view illustrating diagrammatically theset-up and principle of operation of the machine illustrated whenlapping the concave'surface of one type lens; i

Fig. 5 is a plan view further illustrating diagrammatically theoperation of the machine;

Fig. 6 is a diagrammatic view, similar to that of Fig. 4, showing aset-up for lapping the concave surface of a lens having a smaller, moresharply curved surface than the lens shown in Fig. 4; and

Fig. 7 is a diagrammatic view illustrating the set-up and operation'ofthe machine in lapping a convex surface on alens.

2,97?,'i24 Patented Apr. 4, 1961 Referring now to the drawings bynumerals of reference, 10 denotes the base or frame of the machine.Secured by means of screws 21 (Fig. 1) in an opening 11 in the base 10is a support 12 in which there is journaled on 5 spaced anti-frictionbearings 13 and 14 a tool spindle 15. The tool spindle is adapted to bedriven from a motor 16, which is mounted on top of the frame, throughthe'armature. shaft 17 of the motor, a pulley 18, the belt 19, and apulley 20. Pulley 20 is keyed or otherwise fastened to 10 the lower endof the tool spindle 15. The lap for lapping the lens is keyed, orotherwise fastened, to an adapter 26 that is threaded, or otherwisesecured to the spindle 15. A guard 27 is fastened to the adapter and issecured by the adapter to the spindle 15 to cover the 10 top of thespindle to prevent abrasive or other grit from getting into the spindlebearings; and a guard 29 is secured to the support12 around the tool andlens to prevent splattering of the abrasive compound.

Mounted on the base 10 to be adjustable laterally recti- 20 linearlythereon is a column 30 (Figs. 1 and 2). This column is adapted to beadjusted laterally on the base on 1 which pass through elongate slots 39in the column, and

which thread into the base. 30 Journaled in the column 30 is a trunnion45 (Fig. 1).

This trunnion is adapted, to be secured in any position to which it isadjusted angularly about its axis, by a clamp plate 48 which is adaptedto be held in clamping engagement witha fiat surface, formed on the rearof the column 30, by a bolt 46 that threads into the trunnion.

The plate 48 is held against rotational movement relative to thetrunnion by means of a dowel pin 47.

Secured to the trunnion to be adjustable therewith about theaxis of thetrunnion is a bracket 50. The- 4 bracket 50 is held against axialmovement relative to the trunnion by a split ring 51 which engages in aperipheral recess in the trunnion. It is adapted to be secured againstmovement angularly relative to the trunnion by a setscrew 53 whichengages in an elongate recess 54 in the 45 periphery of the trunnion.

Mounted on the bracket 50 for oscillatory movement thereon about an axisat right angles to the axis of the trunnion is a carrier 60. The bracket50 has two parallel ears 61 and 62 integral with it and projecting 50forwardly from it. Secured in these cars 61 and 62 with a pressed fitare two axially aligned trunnion pins 63 and 64. The carrier 60 ismounted on these trunnion pins by means of bushings 65 and 66 which aremounted in spaced ears 73 and 74 formed integral with and projectingrearwardly from the carrier. The nut 67, which threads into one ear 73of the carrier, serves to hold the carrier in position on the bracket59. This nut 67 is provided with a plurality of angularly spacedperipheral notches 68, which are adapted to be engaged by the head 0 ofa screw 69 to secure the nut in any adjusted position.

The screw 69 threads into the rocker member 60.

Mounted on the carrier for rectilinear adjustment thereon axially of theaxis of oscillation of the carrier is an air cylinder 70. This cylinderis adjustable on the front face of the carrier and is guided in itsadjustment by a key or gib 71 (Fig. 2). It is adapted to be secured tothe carrier in any adjusted position by bolts 72 which pass throughelongate slots in the carrier and thread into the base of the aircylinder.

Reciprocable in the air cylinder is a piston 75 (Fig. 1) which issecured to a piston rod 76. This piston rod projects beyond both sidesof the piston. It extends at its upper end through a guide bushing 77and through a suitable packing seal 79 in the end cap 78 of thecylinder. It has a stop block 80 secured to its upper end to limit itsdownward movement. It extendsat its lower end through a guide bushing 81and through a conventional seal 82 in the end cap 83 of the cylinder.The end caps 78 and 82 are secured to the cylinder body by screws or inany other suitable manner. At its lower end the piston rod 76 has aball-headed member 85 threaded therein. The ball head of the member 85is adapted to engage in a complementarily-shaped socket formed in a lensblock 86, to which the lens L, which is to be lapped, is secured bypitch or in any other suitable manner. The ball head of the member 85and the socket of the lens block form a ball and socket joint. Airpressure is adapted to be applied to the upper face of the piston 75 tohold the lens in engagement with the lap during the operation of themachine.

Oscillatory motion of the carrier 60 is effected by reciprocation of apiston 90 (Fig. 3) in a cylinder 91. The piston is secured to a pistonrod 92 which projects at both ends through the end caps 93 and 94,respectively, of the cylinder. The piston rod slides through bushingsand sealing members in these end caps. The piston rod engages atopposite ends with two stop screws 95 and 96 that are threaded to thearms of a yoke 97, and secured therein by nuts 98.

The hydraulic cylinder 91 is supported from the bracket 50, beingsecured to the bracket by screws 99 that thread into the base of thecylinder. The bracket is formed with spaced guides 100 and 101; and thebase of the cylinder 91 is secured to these guides by the screws 99. Theyoke 97 moves in its reciprocatory movement between the guides 100 and101. Fastened to the yoke 97 is a stud or pin 105 on which there ismounted a block 106. The carrier 60 is furcated at its rear end; and theblock 106 engages in the recess 104 between the furcations of thismember, thus transmitting the reciprocatory motion of the piston 90 tothe carrier 60 to rock that member about the axis of the trunnion pins63 and 64. The yoke member 97 has aligned, spaced lugs 107 projectingrearwardly therefrom. Mounted to rotate in these lugs is a screw shaft108, which is adapted to be manually rotated by means of the knob 109.The shaft has right and left hand threads, respectively, at oppositesides of its longitudinal center. Adjustably mounted on this screw shaft108 are two knurled blocks 110, which are adapted to be adjusted alongthe shaft a desired distance apart. These blocks are positioned toengage the lug 111 of a cam plate 112, which is slidably mounted on therear face of the base of the cylinder 93, and which is secured theretoby bolts 114. These bolts thread into the base, and pass throughelongate slots 115 in the cam plate. The cam plate is formed with abottom cam surface adapted to engage the plunger of a conventional limitswitch 120 that is wired in electric circuit with the solenoid of aconventional solenoidoperated valve (not shown) that controls thedirection of flow of the hydraulic motive fluid to the cylinder 91. Thelimit switch 120 is mounted on a plate 121 which is secured to thebracket 50 by the bolts or studs 114. A coil spring 122, which surroundseach bolt 114, is interposed between a shoulder on the bolt and theplate 121 to frictionally hold the cam plate 112 in position.

The hydraulic motive fluid may be supplied from the line common to aplurality of machines, or from a pump 124 (Fig. 1) mounted on top of themotor 16 and driven from the armature shaft of the motor. The armatureshaft of the motor projects at both ends beyond the motor housing.

In operation, the bracket 50 is adjusted with trunnioninsure that theair pressure is applied normal to thelap surface. The column 30 is alsoadjusted laterally on the base 10 so that the center of the stroke ofoscillation of carrier 60 about the axis of pins 63 and 64 will beapproximately mid-way between one edge of the lap and the axis of thelap so that the lens will move in its oscillation from one edge to thecenter of the lap back and forth.

Fig. 4 illustrates diagrammatically the set-up and operation for lappinga concave surface on a lens L. The lens L is cemented or otherwisesecured to the lens block 86, and a lap 25 is used that has a convexgenerally spherical operating surface 125 centered at 126 on the axis127 of the lap spindle 15. For lapping this lens L the column 30 isadjusted laterally on the base 10 by a distance 130 so that the pivotaxis 131 of the bracket 50 (the axis of trunnion 45) is offset by thisdistance 130 from the axis 127 of the lap spindle. Then the bracket 50is adjusted angularly about the axis 131 until the center line 132 ofthe piston 76 is normal to the lap surface 125 and intersects the axis127 of the lap spindle in the center 126 of the lap surface. When themachine is operating, then, the reciprocating piston 90 rocks thecarrier 60 back and forth about the axis 135 (Fig. 5) of the pins 63 and64, causing the air cylinder and the lens to oscillate through an angle136 about this axis 135. The air pressure on the top of piston 75 holdsthe lens in lapping engagement with the lap during this rocking motion,the piston 75 moving in cylinder 70 to maintain this lapping engagement.The piston 90 operating through the yoke 97, and the nuts 110 shifts thecam 112 at opposite ends of the movement of the piston to operate thelimit switch 120, which reverses the valve that controls the directionof application of the fluid pressure to the piston 90.

The air pressure is maintained on piston 75 during the entire operationof the machine. It may be supplied from any suitable source ofcompressed air through a conduit (not shown) that threads at 102 intocylinder 70. The air pressure on the top of the piston 75 can bereleased when desired through this same opening 102. A conventionalvalve may be used for this purpose.

For a lens L (Fig. 6), which has more concavity, a lap 25' will be usedwhich has a shorter radius of curvature, that is, greater convexity.Here the column 30 will be adjusted laterally on the base 10 a distance140 less than the distance 130 so that the axis 131 of trunnion 45 willbe offset this distance 140, and then the cylinder 70 is tilted aboutthis axis 131 so that the center line 132 of piston rod 76 will benormal to the operating surface of the lap and will intersect the axis127 of the lap spindle in the center 146 of curvature of the lap surface145. The amount of oscillatory movement of the lap is again determinedby adjustment of the nuts 110. A graduated dial 128 (Figs. 2 and 3) maybe secured to the spindle 108 to read against a pointer 129 that isfastened to one of the lugs 107 so that this adjustment can be madeprecisely. As before in the lapping operation the lap will rotate on itsaxis, and the lens will be oscillated about an axis 135 parallel to theaxis 127 of the work spindle 76, the amount of oscillation dependingupon the positions of the nuts 110.

For lapping a convex lens, such as shown at L in Fig. 7, a concave lap25" will be employed whose lapping surface is denoted at 155. In thiscase the column 30 is adjusted laterally to the right, as viewed in Fig.7, of the axis 127 of the lap spindle by a distance 150, and the bracket50 is adjusted about the axis 131 of the trunnion 45 until the centerline 132 of the piston 76 intersects the axis 127 of the lap spindle inthe center 156 of curvature of the operating surface of the lap. Then,as before, lapping is effected by rotating the lap on its axis inengagement with the lens while the lens carrier 60 is oscillated aboutthe axis 135 (Fig. 5) of the carrier.

From the preceding description it will be seen that because theoscillation of carrier 60 is effected by a recipe.

rocable hydraulically-actuated piston 90, we have provided a very simplemachine with a velocity of stroke that is constant throughout its entirelength, and in which the reversal of the oscillating motion at the endsof the stroke is practically instantaneous. Thus, it will be seen, thatwe have provided a machine with which it is possible to produce lensesthat arefree of zones or aberration.

While the invention has been described in connection with a specificembodiment thereof, however, it will be understood that it is capable offurther modification, and this application is intended to cover anyvariations, uses, or adaptations of the'invention following, in general,the principles of the invention and including such departures from thepresent disclosure as come within known or customary practice in the artto which the invention pertains and as may be applied to the essentialfeatures hereinbefore set forth, and as fall within the scope of theinvention or the limits of the appended claims.

Having thus described our invention, what we claim is:

1. A lens surfacing machine comprising a base, a column adjustablerectilinearly in said base, a bracket mounted on said column for angularadjustment thereon, a carrier mounted on said bracket for oscillationabout an axis extending at right angles to the axis of adjustment ofsaid bracket, a spindle mounted in said base, and a spindle mounted insaid carrier, one of said spindles being adapted to carry an abradingtool and the other spindle being adapted to carry a lens, one of saidspindles being rotatable and the other of said spindles being axiallyreciprocable, said bracket being adjustable angularly on said columnabout an axis extending at right angles to the direction of lateraladjustment of said column, so that the axis of the spindle which ismounted on said carrier means for rotating one of said spindles on itsaxis, fluidpressure operated means for constantly urging the otherspindle axially toward said one spindle to hold the lens and abradingtool in operative engagement, and means for oscillating said carrier onits axis simultaneously with the rotation of said one spindle.

2. A lens surfacing machine comprising a base, a tool spindle journaledin said base, means for securing an abrading tool to said spindle at oneend thereof, a column adjustable rectilinearly on said base in adirection at right angles to the axis of said spindle, a bracket mountedon said column for adjustment thereon about an axis at right angles bothto the axis of said spindle and to the direction of adjustment of saidcolumn, a carrier mounted on said bracket for oscillation about an axisat right angles to the axis about which said bracket is adjustable, arod mounted on said carrier for movement in a direction parallel to saidaxis of oscillation, means for securing a workpiece to the end of saidrod adjacent the tool, means for constantly urging said rod in adirection to hold said workpiece and tool in operative engagement underpressure, means for rotating said spindle, and means for simultaneouslyoscillating said carrier.

3. A lens surfacing machine comprising a base, a tool spindle journaledin said base for rotation thereon, means for securing an abrading toolto said spindle, a cylinder, a piston reciprocablein said cylinder, apiston rod secured to said cylinder and projecting at one end beyond oneend of said cylinder, means for securing a lens to the projecting end ofsaid piston rod, means for adjusting said cylinder on said base so thatthe longitudinal center line of said piston rod intersects the axis ofsaid spindle in a point offset from the zone of engagement of the tooland lens, means for applying air pressure to one end of said piston tohold said tool and lens in engagement under pressure, means for rotatingsaid spindle, and means for simultaneously oscillating said cylinderabout an axis parallel to the longitudinal center line of said pistonrod.

4. A lens surfacing machine according to claim 3 in which saidoscillating means comprises a second cylinder, a second pistonreciprocable in said second cylinder, and means for applying hydraulicpressure alternately to 6 opposite sides of said piston to swing thefirst-named cylinder first in one direction and then in the other at auniform velocity, means actuated by the relative movement between saidsecond piston and said second cylinder for reversing said oscillatingmeans, and means adjustable to control the stroke of said oscillatingmeans. 5. A lens surfacing machine comprising a tool support,

a work support, means for securing an abrading tool to said toolsupport, means for securing a workpiece to said work support, means forconstantly urging one of said supports toward the other to hold the tooland workpiece in operative engagement under pressure, means foradjusting said one support angularly relative to the other support sothat the pressure is applied normal to the operating surface of thetool, means for rotating one of said supports, andhydraulically-actuated means including a cylinder and a pistonreciprocable therein for oscillating one of said supports simultaneouslywith said rotary movement about an axis parallel to the direction ofapplication of pressure.

6. A lens surfacing machine comprising a base, a tool support journaledin said base, a work support mounted on said base for rectilinearreciprocating movement, means for securing an abrading tool to said toolsupport, means for securing a workpiece to said work support, means forconstantly urging said work support toward said tool support to hold thetool and workpiece in operative engagement under pressure, means foradjustingsaid work support angularly so that the pressure is applied ina direction normal to the operating surface of the tool, means forrotating the tool support, and hydraulically-actuated means including acylinder and a piston reciprocable therein for simultaneouslyoscillating said work support about an axis parallel to the axis ofapplied pressure.

7. A lens surfacing machine comprising a base, a tool spindle mounted onsaid base to rotate on a vertical axis, means for securing a lappingtool to the upper end of said spindle, a column adjustable rectilinearlyon said base in a horizontal direction, a bracket mounted on said columnfor angular adjustment about a horizontal axis extending at right anglesto the direction of adjustment of said column, a carrier mounted on saidbracket for oscillation about an axis extending at right angles to theaxis of adjustment of said bracket, a cylinder secured to said carrier,a piston reciprocable in said cylinder in a direction parallel to theaxis of oscillation of said carrier, a piston rod secured to said pistonto project through the lower end of said cylinder, means for securing alens to the lower end of said piston rod, means for applying airpressure to the upper face of said piston to urge said lens intoengagement with said tool under pressure, means for rotating said toolspindle, and means for simultaneously oscillating said carrier includinga second cylinder, a second piston reciprocable therein, means forapplying hydraulic pressure alternately to op posite sides of saidsecond piston to effect swinging movement of the lens over the operatingsurface of the tool alternately in opposite directions at a uniformvelocity and to effect practically instantaneous reversal of saidswinging movement at opposite ends of the swinging stroke, and meansactuated by the relative movement between said second piston and saidsecond cylinder for reversing said oscillating means at opposite ends ofthe stroke of said second piston in said second cylinder.

References Cited in the file of this patent UNITED STATES PATENTS1,659,277 Maynard Feb. 14, 1928 2,286,361 Goddu June 16, 1942 2,381,449Holman Aug. 7, 1945 2,643,492 Burroughs June 30, 1953 2,649,667 CookeAug. 25, 1953 2,880,555 Brueckner et a1. Apr. 7, 1959 FOREIGN PATENTS977,720 France Nov. 15 1950

